1. Field of the Invention
This application relates generally to user interfaces, and particularly to user interfaces for portable biometric identification systems.
2. Description of the Related Arts
Biometric systems allow for the identification of human subjects using human traits that are either unique to each subject or are sufficiently uncommon so that one or more traits can be used to narrow down the number of possible subjects matching those traits. There are a number of different kinds of traits that may be used in biometric identification including, for example, iris images, face images, fingerprints, and recordings of a subject's voice. Traits captured in some form for use in biometric identification may be referred to generally as biometric identifiers.
However, capture of biometric identifiers is a difficult task. Each type of biometric identifier captured needs to be of sufficient quality that it can be used to narrow down the number of possible subjects matching the corresponding trait. A biometric identifier of sufficient quality may also be referred to as a “valid” biometric identifier. If the biometric identifier is of insufficient quality, it may not be possible to accurately or precisely determine whether the biometric identifier is associated with a given human subject. A poor quality biometric identifier may be entirely useless, or only of limited use in narrowing down the subjects matching the biometric identifier.
Systems configured for the capture of a biometric identifier will generally be designed for a specific manner of use that improves the chance of capture of a valid biometric identifier. Generally, a user of the system will follow a specific set of instructions designed to ensure the capture of a valid biometric identifier. For example, in the capture of fingerprints by paper and ink, the finger is usually rolled from one side to the other on the paper without repeating to avoid smudging. The paper includes instructions for the user to ensure that fingerprints captured are for the correct fingers with respect to the paper. For face images, the subject must look a particular direction and must be sufficiently still in order to capture all necessary facial features. For iris images, existing iris capture systems generally only work within a limited range of distance, under certain light conditions.
While in some cases the instructions for biometric capture are explained by text, often times the instructions are not written down and must be learned through training and experience. This increases the difficulty of capturing valid biometric identifiers. These requirements can be particularly onerous if the user is working in a hostile environment (e.g., in the working environments of the police or military) where subject cooperation is difficult to obtain. In these circumstances, the more difficult the biometric identifier capture process is, the greater the risk of personal harm to the user.